This invention relates to tri-axial accelerometers.
For measurement of three mutually transverse components of acceleration or applied force, such as the components of the earth's gravitational field g, it is known to use a tri-axial accelerometer package comprising three single-axis accelerometers arranged so that their axes of sensitivity are mutually orthogonal. Each accelerometer comprises a respective permanent magnet displaceable with respect to a null position along its axis of sensitivity, and sensing means for detecting such displacement and for providing an output signal indicative of the component of the applied force along the axis of sensitivity.
However, when the outputs of the three accelerometers of such a package are used to perform a calculation, for example in order to determine the inclination of a borehole, it is necessary to determine the magnet temperature coefficient of each accelerometer and to apply appropriate corrections to compensate for differences in the variation of the scale factors of the three accelerometers with temperature, since the magnet temperature coefficients of the three accelerometers will differ.
It is an object of the invention to provide an improved form of tri-axial accelerometer.